These are the commercial jet engines you see, like the Boeing 777, 747, Airbus A330 and A380s. Though there is a considerable reduction of the engine thrust, at these altitudes the lower drag associated with low air density means a more economical flight with a higher True Air Speed.
Crepitus in the knees may be caused by knee injuries such as meniscus tears. These are fairly common in people who play sports, jog, or run. A meniscus tear can cause crepitus as the joint moves. Chondromalacia patella is a dull ache behind the kneecap, usually caused by overuse or injury. There will be damage to the undersurface cartilage covering the kneecap.
RE: what causes the dicrotic notch? any one know what causes the dicrotic notch (read from the pulse integral channel from the heart) ? i know it reflects the cessation of systole..Follow.est Answer: Sudden closure of the aortic valve, causes a momentary elevated rebound in the pressure reading, such that the smooth downward slope of the pressure waveform is interrupted by a very brief upward movement; forming a sawtooth notch.